I am trying to access National Weather Service forecasting data through the
rNOMADS package. I’m not sure if the Weather Service software – grib2 – loaded
correctly. Second, some of the examples in the rNOMADS documentation seem to
run correctly but I’m not sure what the output means. Any anvise would be
greatly appreciated.
1 - I tried to load the wgrib2 software from instructions in the following
website:
https://bovineaerospace.wordpress.com/2015/04/26/how-to-install-rnomads-with-grib-file-support-on-windows/
2 – the instructions say that if it loaded correctly I should get a laundry
list similar to what is below from the command: >system(“wgrib2”).
The list I get looks different. Below is the first 20 or so entries. How can
I check to see if the wgrib2 loaded correctly?
wgrib2 v0.1.9.9 9/2013 Wesley Ebisuzaki, Reinoud Bokhorst, Jaakko Hyvätti,
Dusan Jovic, Kristian Nilssen, Karl Pfeiffer, Pablo Romero, Manfred Schwarb,
Arlindo da Silva, Niklas Sondell, Sergey Varlamov
-0xSec inv X Hex dump of section X (0..8)
-MM inv reference time MM
-N_ens inv number of ensemble members
-RT inv type of reference Time
-S inv simple inventory with minutes and seconds (subject
to change)
-Sec0 inv contents of section0
-Sec3 inv contents of section 3 (Grid Definition Section)
-Sec4 inv Sec 4 values (Product definition section)
-Sec5 inv Sec 5 values (Data representation section)
-Sec6 inv show bit-map section
-Sec_len inv length of various grib sections
-T inv reference time YYYYMMDDHHMMSS
-V inv diagnostic output
-VT inv verf time = reference_time + forecast_time
(YYYYMMDDHHMMSS)
-YY inv reference time YYYY
3 – As I said, some of the documentation examples work and for some I get error
messages. Below is an example of one that seemed to work but I don’t
understand the output.
#GribInfo - page 20
urlsOut <- CrawlModels(abbrev="gfs_0p50",depth=2)
ModelParameters <- ParseModelPage(urlsOut[2])#[1] is most recent model
MyPred <- ModelParameters$pred[grep("06$",ModelParameters$pred)]
Levels <- c("2_m_above_ground","800_mb")
Variables <- c("TMP","RH")
GribInfo <- GribGrab(urlsOut[2],MyPred,Levels,Variables)
GribInv <- GribInfo(GribInfo[[1]]$file.name,"grib2")
The command GribInv$inventory returns:
$inventory
[1] "1:0:d=2020070606:TMP:800 mb:6 hour fcst:"
"2:148450:d=2020070606:RH:800 mb:6 hour fcst:"
[3] "3:414132:d=2020070606:TMP:2 m above ground:6 hour fcst:"
"4:571266:d=2020070606:RH:2 m above ground:6 hour fcst:"
This is supposed to be temperature and relative humidity 2 meters above the
ground and at 800 milibars for 2020 – July 6 – at ZULU time 0600. But I have
no idea what the numbers 414132 – second line – mean.
Any advise would be greatly appreciated.
Philip Heinrich
From: stephen sefick
Sent: Thursday, July 2, 2020 3:20 PM
To: Philip
Cc: r-help
Subject: Re: [R] National Weather Service Data
I am unfamiliar with Rnomads. Could you provide a minimal reproducable example?
You are more likely to receive help this way.
On Thu, Jul 2, 2020, 18:06 Philip <herd_...@cox.net> wrote:
Is anyone out there familiar with rNOMADS? It is a package to get into
National Weather Service forecasting data with R?
I'm not sure the Weather Service software named wgrib2 loaded correctly
because some of the stuff won't run and I can't make much sense out of some of
the output.
Thanks.
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